TOL. XII.] PHILOSOPHICAL TRANSACTIOWf. 383 



on design. When we held both his hands, and caused another to make such 

 motions, he pressed to get free : but, when we would have known more parti- 

 cularly how he found himself affected, he could only give us this simple answer, 

 that it vexed his heart and his brain. 



I took occasion lately to visit a poor woman in the neighbouring parish, who 

 has been long afflicted with the gravel, and has passed four stones of an unusual 

 size ; of which I have one by me, which though it be not the largest of the 4, 

 is yet more than 5 inches about the one way, and 4 the other. They are all 

 oval ; the first and a part of the second were smooth ; but the other two very 

 rough ; and the last the largest, which came away about Christmas last, was 

 bloody on one side when I saw it. This puts me in mind of that stone of a 

 prodigious size, which was found last year in a gentleman's bladder in this 

 country, after his decease, weighing 32 ounces. 



M. Leewenhoeck^s manner of observing the Animalcula in divers Sorts of Water, 



N' 1 34, p. 844. 



I thus order my division of the water, and the enumeration of the animalcula : 

 I suppose that a drop of water equals a pea in bulk ; and I take a little quantity 

 of water of a round figure, as large as a millet-grain ; this I reckon to be the 

 -gV part of a pea: for when the axis of a millet-seed makes 1, that of a pea 

 makes 4-l : whence it follows, that the grain of a millet is at least the -gV part 

 of a pea, according to the received rules of mathematicians.* This small 

 quantity of water I gather up into a very slender glass-pipe, dividing by this 

 means that little water into 25 or 30 parts, of which I observe one part after 

 another, and show the same to others. 



Other spectators, as well as myself, judged that in -^ part of the water, 

 equalling the bulk of a millet-seed, he saw more than 1000 living animals : but 

 they wondered much more, when I said I saw in it two or three kinds of much 

 smaller animals besides, which did not appear to them, because I saw them by 

 another microscope, which I still reserve to myself alone. Hence it is manifest, 

 that if in the -^ part of one millet-seed there are seen 1000, there may be seen 

 30,000 in one such whole seed, and consequently in a drop of water, which is 

 91 times larger than such a seed, there may be seen 2,730,000. For, 4-i- X 4-i- 

 X 4-i- = 9H; and gi X 30,000 = 2,730,000. 



Otherwise, I compare the quantity of the water to the bulk of a grain of sand ; 

 in which quantity of water I doubt not at all that I see more than 1000 ani- 

 malcula. Now if the axis of a grain of sand be 1 , the axis of a drop of water 



* That is, by cubing the diameters. 



